You're missing the point—it's unlikely that you need to do anything at all; the Windows APIs handle forward slash as a path separator just fine.
And on that note, for any MS employees reading now and who write READMEs and other docs for projects with publicly released code in this "New Microsoft" era, please default to using forward slash for the paths in your code snippets, instead of backslash. There's hardly any reason not to. (Unless you're using the command prompt—but you guys are a pointy clicky bunch and don't like the CLI anyway, right? Even so, you have PowerShell.)
So you can drop practice of writing up separate "For Windows users" and "For Mac and Linux users" instructions that differ only in the type of path separator used. Just use plain ol' slash.
Please tell your colleagues to do the same.